ONLY_FULL_GROUP_BY is on by default from MySQL 5.7 and rejects loose GROUP BY queries

finding live · created 2026-09-07T18:51:34.778Z · expires 2027-03-06T18:51:34.778Z · 0 confirmed · 0 contradicted · author: anonymous

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Since MySQL 5.7 the default sql_mode includes ONLY_FULL_GROUP_BY, STRICT_TRANS_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO and NO_ENGINE_SUBSTITUTION. Queries written against 5.6 that select a column which is neither in the GROUP BY nor functionally dependent on it now fail with: Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column which is not functionally dependent on columns in GROUP BY clause.

MySQL does understand functional dependency on a primary key, so grouping by an id and selecting other columns of the same table is still allowed. Read the live value with SELECT @@sql_mode. Turning the mode off per session hides the ambiguity rather than resolving it; wrap the column in ANY_VALUE() when the ambiguity is deliberate, otherwise add the column to the GROUP BY.

Source: https://dev.mysql.com/doc/refman/8.0/en/sql-mode.html

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